If you receive the following error when trying to connect to Exchange Online via PowerShell, then you will need to upgrade the Connect-ExchangeOnline PowerShell module.
AADSTS50011: The reply URL specified in the request does not match the reply URLs configured for the application

Resolving AADSTS50011 for Connect-ExchangeOnline
To resolve, launch PowerShell and run the following command. If you do not trust the PowerShell gallery you may also be prompted to confirm the installation from an untrusted gallery. Press “Y” to confirm.
C:\> Update-Module ExchangeOnlineManagement You are installing the module from an untrusted repository. If you trust this repository, change its InstallationPolicy value by running the Set-PSRepository cmdlet. Are you sure you want to install the module from 'PSGallery'? [Y] Yes [A] Yes to All [N] No to All [S] Suspend [?] Help: Y
At this point, it is best to close and reopen any PowerShell windows you had open and reissue the command Connect-ExchangeOnline. The issue should now be resolved.
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